New software for the Sony PSP will allow users to use a GPS accessory for outdoor geolocation and then switch to indoor geolocation provided by a Wi-Fi signal when in a building.
The new navigation software from Zenrin Map 2 and the Edia Maplus will still use the GPS accessory for the PSP, but add location data provided through Wi-Fi. For instance if the PSP is connected to a Wi-Fi hotspot, the navigation applications can continue to show the location inside buildings where GPS satellites are not reachable.
You can buy the Japan-only GPS receiver stateside from Play-Asia for $59.90 or order a GPS device with the Zenrin software or Edia software for $95 or $99.90, respectively.